The broad aim of this application is to examine circadian timing and daytime function in high school students in the context of weekend recovery sleep behavior. Large disparity between school night and weekend night sleep timing is associated with poor daytime function (e.g., poor academic grades and depressed mood). The first aim of this study is to examine circadian factors that may contribute to this association. Modifying sleep patterns on the weekend to maintain stable circadian timing may attenuate daytime function decrements. Thus, the second aim of this study is to test an alternative weekend sleep schedule that stabilizes the circadian system. The proposed study uses a within subjects counterbalanced design with two conditions that differ only by the following enforced weekend sleep/wake schedules: the commonly observed, late rise time schedule and an alternative schedule with stable nocturnal sleep and an afternoon nap. Circadian phase, subjective sleepiness, cognitive throughput, mood, and vigilance assessments precede and follow each weekend condition. This study may further the understanding of risk factors for poor daytime function and will evaluate sleep behaviors that may attenuate these decrements in teens. [unreadable] [unreadable] [unreadable]